When producing consumer products from different vegetable or animal oils deodorisation is a part in the refining process. During the deodorisation the oil is heated to a high temperature 180-275.degree. C. in order to drive off volatile impurities and undesired substances from the oil. These substances have a lower boiling point than the different triglycerides which constitute the fatty oil. The deodorisation is carried through under vacuum conditions, 1-20 mbar absolute pressure, and the removal is facilitated by addition of deodorisation gas to the oil. The gas facilitates the removal of undesired substances.
On the market there are today a large number of different deodorisation plants, both for continuous flow through the plant and with a batchwise treatment of the oil. During continuous deodorisation the oil usually flows over a number of trays or containers which are stacked vertically in a circular shell manner. In the bottom of the trays or containers there are means for addition of gas. Alternatively the gas may be added by using a means with siphon effect. Oil and gas are forced upwards in an ejector tube towards a deflection plate and is finely divided against the same. The oil is added to the vessel in the upper part of the plant and flows from an upper container to the next container. In order to control the flow through the containers these are provided with screening plates, such that the oil flows from an inlet at a certain place in the container to an outlet in another place. The holding time in the vessel is set to a certain value depending on the geometry of the flow channels. The switch-over time between different products is long.
When the deodorisation is carried through in batches all operations (distillation and heat holding for bleaching) usually take place in the same vessel. This method of working makes rapid changes between different oil products possible, but the holding time is long since it depends both on distillation and heat transfer effect.